Router guard

Abstract: A router (21) has a base (70) joined to a body (60) by columns (62,64), the latter being slidable in sleeves (66) in the body (60). A spring (90) between the base (70) and the body of the router serves as a guard for the router bit (76).

Description: This invention relates to routing machines, and particularly to guards therefor and especially to such routers for use in machining centres. A machining centre usually comprises a work table on which a processing tool, for example, a router or milling cutter, moves along three Cartesian axes. The centre may be controlled by a computer, e.g. a personal computer, in which must be first installed a processing program. A vertical guide supports a first carriage which runs along the guide by means of a first motor. The tool is fixed to the first carriage. The vertical guide is supported by a second carriage, running by means of a second motor along a first horizontal guide which is supported at one end by a third carriage running by means of a third motor along a second horizontal guide. The second horizontal guide is arranged at a right angle to the first horizontal guide, and the support moves along the three Cartesian axes over the horizontal work table. The three motors are connected to the computer, which may be integrated in the machine and may comprise a microprocessor sending to the motors signals for movement by reading position and movement data from memories connected thereto. In stationery machinery, such as the type to which the present invention relates, and where the tool is a standard router, as known, for example, from EP-A-473 035, or indeed any milling tool, it must be provided with guarding in order to protect operators from inadvertently contacting the tool bit and possibly injuring themselves. Such guarding is not normally available for hand held routers because the operator must hold the router and consequently has no occasion to insert his/her hand into contact with the tool bit. Consequently, it is an object of the present invention to provide a router which overcomes these disadvantages, or at least mitigates their effects. In accordance with this invention, there is provided a router comprising a body which houses a motor driving a rotary tool bit depending from said body, at least one column being slidable with respect to said body along an axis parallel the rotation axis of said bit and mounting a router base having an aperture through which said tool is adapted to plunge to perform cutting operations, and a guard comprising a coil spring between said base and body and surrounding said bit axis. Needless to say, to be effective, the spring should have a pitch when fully extended which is insufficient to permit easy insertion of a standard finger between adjacent turns of the spring. Preferably, said spring is employed as the return spring for said base, and serves to bias the base and body apart. The present invention has particular application in the machining centre described above. To further clarify the explanation of the innovative principles of the present invention and its advantages as compared with the known art there is described below with the aid of the annexed drawings a possible embodiment as nonlimiting examples applying said principles. In the drawings:- Figure 1a shows schematically a perspective view of a machining centre of the type to which the present invention relates; Figure 1b shows a fragmentary view, partly in section along the line II-II in Figure 1a; Figure 1c is a section on the line III-III in Figure 1a; Figure 2 shows a fragmentary view partially cross sectioned of a first carriage of a machining centre according to the present invention; Figure 3 shows an underneath view of the carriage of Figure 2, and Figures 4 a to e show different views of a spring guard according to the present invention, 4a being a view in the direction of Arrow a in Figure 4b, 4b being a side view, partly sectioned along the line b-b in Figure 4e, 4c being a view in the direction of Arrow c in Figure 4b, 4d being a side view, partly sectioned along the line b-b in Figure 4e, and 4e being a section on the line e-e in Figure 4d. With reference to the drawings, Figure 1a shows a machining centre indicated generally by reference number 10, comprising a work table 11 on which is present a support 12 moved vertically along a first guide 13 powered by a first motor 14 or Z axis motor. The vertical guide 13 is in turn movable along a horizontal guide 15 by means of a second motor 16 or X axis motor. The guide 15 is supported at the ends by two guides 17,18 arranged horizontally at right angles thereto. The guide 15 is thus movable horizontally along said guides 17,18 by means of a third motor 19 or Y axis motor. The motors 14,16,19 are operated by an electronic circuit having a control panel or module 20, supported in a container at the end of a jointed arm 34 which can also constitute internally a passage for the electrical connections. The support 12 receives an electric tool of the known art and therefore not further described nor shown, such as for example a mill or router, drawn in broken lines and indicated in Figure 1a by reference number 21. To this end the support can include known complementary couplings with couplers in the tool. In Figure 1b is shown schematically a cross section of the device 10 taken along the guide 15. As may be seen in said figure, the guide 15 is made from a boxed section in which runs a carriage 22 moved by a screw 23 operated by the motor 16 through a speed reducer 24. The carriage 22 has a part 25 projecting from the guide through a longitudinal slot 26 to terminate with a supporting end 27 to which is fixed the vertical guide 13. The guide 13, also provided in boxed form comprises a screw 28 moved by the motor 14 through a speed reducer 29. On the screw 28 runs a nut screw carriage 30 to which is fixed through a groove 31 (Figure 1a) the support 12 for the tool. To prevent penetration of dust or processing chips inside the guide 15, the slot 26 is closed by a flexible strip 32 which is raised and moved away from the slot only opposite the end of the support 27 to pass through a passage 33 therein. In this manner the part 25 can project from the slot 26, elsewhere closed by the strip 32. As may be seen in Figure 1c, the carriage 22 has roller bearings 35 for guided running along complementary grooves 36 inside the guide 15. The guide 17 is substantially identical to the above described guide 15. For this reason the analogous elements will be indicated below with the same numbering used above but with the addition of the suffix "prime". As may be well seen in Figures 1b and 1c the guide 17 is provided with a boxed section in which runs a carriage 22' moved by a screw 23' operated by the motor 19 through a speed reducer 24'. The carriage 22' has roller bearings 35' for guided running along complementary longitudinal grooves 36' inside the guide 17. In addition, the carriage 22' has a part 25' projecting from the guide through a longitudinal slot 26' to terminate with a supporting end 27' to which is fixed one end of the horizontal guide 15. To prevent penetration of dust or processing chips into the guide 17 the slot 26' is closed by a flexible strip 32' passing through a passage 33' in the supporting end 27'. As may be well seen in Figure 1b, the guide 18 is provided merely with a boxed section in which is arranged a track 37 on which runs an idling wheel 38 supported on the guide 15 by means of a support 39 projecting from the guide 18 through a longitudinal groove 40, also advantageously closed by a protective strip 41 through the support 39 to allow sliding movement, similarly to what was described for the guides 15 and 17. It is now clear how, by appropriate control of the motors 14,16,19 a tool positioned on the support 12 can be moved to any point on the table 11 and can be brought near to, or be withdrawn from, the table. Turning now to Figures 2 and 3, the carriage 12 comprises an L-shaped bracket in whose horizontal limb 48 is formed a central aperture 50 which has a slot 52 joining the aperture to front end 54 of the bracket 12. Aperture 50 is adapted to receive nose 56 of a router 60 (not fully shown). A screw and bolt (not shown) are adapted to be received in cross bore 58 so as to clamp the nose 56 in the aperture 50. The router 60 has two columns 62,64 which are a sliding fit in sleeves 66 in the body of the router 60. Front column 64 is outside the limb 48 of the bracket 12. Rear column 62 is received, however, through a hole 68 in the limb 48 behind the aperture 50. The columns 62,64 mount a router base 70, and are secured therein by pins 72 passing through bores in the base 70 and columns 62,64. The base 70 has a large central aperture 74, through which a cutter 76, received in the body 60 of the router, is adapted to pass before performing cutting operations on a workpiece below the base 70. The aperture 74 mounts a dust hood 76 which is known per se and is shown only in brief in the drawings. It, too, has a central aperture 78 through which the bit 76 passes, and in the wall of aperture 78, there are formed openings 80 facing the interior of the aperture and which openings lead to a passage 82 in the hood and around the aperture 78 and which ultimately converge on a dust port 84. A vacuum hose (not shown) is adapted to be secured over the end 86 of the port 84 so that vacuum is applied to the aperture 78. Thus dust generated by the tool 76 cutting a workpiece lying against the base 70, at the lower end of aperture 78, is effectively removed. The hood 76 is conveniently constructed from transparent plastics material so that it does not significantly obstruct an operator's view of the workpiece through the aperture 74, and the cutter 76 doing its job. It is a requirement of stationery machinery that its moving parts, at of the cutting tools, be adequately guarded, but this is not a normal requirement for a router. However, the fact that the base 70 is employed in the present invention, provides an opportunity to arrange an effective guard which would otherwise be difficult where the base is not used. Here, a spring 90 is formed between the base 70 and the body 60 of the router. In fact, the spring abuts the underside of the limb 48, rather than the body 60 of the router. The spring 90 has sufficiently tight coils so that the gap between them is insufficient to receive a "standard" finger, and is sufficiently strong that that finger cannot prise the coils apart using a "standard" pressure. On the other hand, the coils must not be so tight that, either they become coil bound when the router is lowered against a workpiece and so that the cutter 76 does not protrude sufficiently below the base 70, or so that they obscure the operator's view of the cutting operation proceeding. Moreover, the spring 90 can replace the normal return springs for the columns 62,64, which can therefore be dispensed with. Indeed, even though routers do not usually have guarding, this arrangement of spring is so convenient and unobtrusive that there is no reason why it should not be employed in normal handheld routers and like machines. In this respect, it is even to be noted that the spring 90 in no way obstructs access to the collet 92 of the router, and which must be loosened, usually with a spanner, in order to change the cutter 76. The spanner can easily slip between adjacent coils of the spring 90. Figures 4 a to e show the spring in several different views. At its lower end, the spring has downwardly depending legs 94, which fit in recesses formed in the base 70. At the top end it has a bulge 96.

Claims: A router comprising a body which houses a motor driving a rotary tool bit depending from said body, at least one column being slidable with respect to said body along an axis parallel the rotation axis of said bit and mounting a router base having an aperture through which said tool is adapted to plunge to perform cutting operations, and a guard comprising a coil spring between said base and body and surrounding said bit axis. A router as claimed in claim 1, in which the spring has a pitch when fully extended which is insufficient to permit easy insertion of a standard finger between adjacent turns of the spring. A router as claimed in claim 1 or 2, in which said spring is employed as the return spring for said base, and serves to bias the base and body apart.

Inventors: BONNETT JOHN, BONNETT, JOHN
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 1994
Main classification: B27C5
IPC codes: B27G21, B27C5